Trying to follow snippets of advice gleaned from magazines and blogs on how to stop heel striking and start landing on my mid or forefoot had left me confused. Any progress made was short-lived and bad habits crept back in as soon as I injected some pace.

While I'm not necessarily convinced that minimalists have had the final word in the running style debate, as an ultrarunner I'm keen to reduce the impact on my body as much as possible – and know that over a 10, 20 or 30-hour race improved efficiency could make a big difference to my performance.

A qualified chi running instructor, the corner stones of Shane's approach are energy efficiency and reduction of impact. "The natural running schools – chi, pose, Alexander – they all pretty much agree how you should run," he said. "They just disagree about how to get there."

Chi running was created in the US in 1999 by Danny Dreyer. Inspired by the Chinese martial art of tai chi, Dreyer's technique is popular with beginners and injured runners, and works on the principle that running with a forward-leaning relaxed posture, an engaged core and fast, light steps leads to less stress on the body, a more efficient style and fewer injuries.

After an introductory chat, Shane shot some video of my pre-chi style. Watching the film back, I could see that my self-taught attempts had somehow resulted in me leaning back, pushing my hips forwards and hitting the ground ahead heel-first on a straight leg – it was kind of painful to watch.

Chi running sets out four steps to a good posture:

1) Stand with your feet pointing straight ahead, a hip-width apart.

2) Lengthen your spine so you're feeling tall – raising your hands in the air above your head and allowing them to fall back can help, especially for corrections as you run.

3) Level your pelvis, which is generally tilted forwards. To do this, place one hand face down on your tummy with the thumb in your belly button and the other hand face up on your back directly opposite, then gently tip your pelvis back to a level position. You should feel your core muscles engage – but don't go so far that your core becomes tense or that your glutes tighten.

4) Place both thumbs on the prominent front hip bone at the top of your legs and pivot forwards from there until you are balanced over your centre of gravity. For me, that meant leaning my top half forwards until I could just see the knot in the laces of my shoes when looking down – an extremely useful reference point which is key to the method for me.

After a bit of practice at achieving good posture, Shane set a metronome at 180 beats per minute and instructed me to lean forwards (pivoting at the ankles) and let gravity do the work of moving me forwards.

A look at the video of my second lap confirms I was landing midfoot on a soft knee. GPS data (from a Garmin 620 with chest strap) shows I was hitting 180 steps per minute and that my "vertical displacement" – basically, how much you bounce – had fallen by 20%. Success!

The rest of the session focused on playing around with lean and arm swing.

The further you lean, the faster you go – moving your head one inch forwards from your starting position corresponds to a slow jog, two inches is aerobic/chatting pace, three inches is anaerobic/race pace and four inches is flat out.

If your cadence is fixed at 180 steps per minute, the way to speed up is to lengthen your stride. Crucially though, rather than stretching your lead leg forwards to lengthen your stride in front, in chi running you land with your feet back from your centre of gravity and lengthen your stride behind.

Shane encouraged me to alter my arm swing too so that the dynamic movement was backwards, rather than forwards. That's taking some getting used to – but I find it helps my heels to kick up higher and lengthen my stride behind.

"After this session, you'll never heel strike again," Shane had told me. I cut my distance back for the first couple of weeks to avoid placing too much strain on my calf muscles and achilles tendons – but I've now built my mileage back up to my usual base level and every step has been on the midfoot. I feel lighter on my feet and when I get it right it feels like I'm running faster for less effort – letting gravity do the work rather than powering away with my quads. Shane may well be right.